The present invention is directed to the field of replacement mufflers, and more specifically to the field of replacement mufflers which can be used to replace original equipment mufflers without requiring any substantial modifications thereto.
It is well known that automotive exhaust systems, and in particular mufflers, are subject to a great deal of physical and thermal stress, and as a result must often be replaced. Indeed, the muffler replacement industry is quite large.
It has been the practice of the larger muffler replacement companies to stock a full line of replacement mufflers which are substantially identical to the original equipment mufflers. By doing so, the original muffler may typically be replaced by separating the tubes or "nipples" on both sides of the muffler from the exhaust and tail pipes, and by reattaching a substantially equivalent structure to the respective pipes. In some cases however, the downstream nipple is not attached to a separate tail pipe, the downstream nipple itself forming the tailpipe or spout. In such case the original muffler is replaced by separating the upstream nipple from the exhaust pipe and by reattaching the substantially equivalent structure thereto. In either case, the resulting exhaust system is essentially a duplicate of the original system. As used throughout the specification and claims, the term "nipple" will be deemed to include the tubes on both sides of the muffler, whether they are attached to exhaust or tail pipes, or whether they form an exhaust pipe or spout without further connection to an external pipe.
Although the above described technique is relatively simple to accomplish, it is expensive since it is necessary to produce and stock from 600 to 800 different kinds of mufflers in order to substantially duplicate the original equipment mufflers for the various makes and models of domestic and foreign automobiles. Further, the storage and inventory requirements are indeed prohibitive for all but the largest replacement muffler manufacturers and installers. Still further, since each type of muffler must be made from scratch and requires a significant retooling of the assemble line, a long lead time is many times required when ordering a particular muffler.
A technique for avoiding the problems associated with the above described procedure employed the use of a "universal" muffler which could be used to replace the original equipment on a wide range of vehicles, thus reducing the inventory and storage requirements associated with the above described procedure. One such universal muffler employed a muffler body having an adjustable length, as disclosed in U.S. Pat. No. 2,382,159 to Klemm. Another type of universal muffler employed the use of nipples which were slidably disposed within the muffler body to effect different length connections between the exhaust and tail pipes. An example of such a system is disclosed in U.S. Pat. No. 3,581,842 to Hall.
Still other types of universal mufflers employed nipples produced from drawing quality aluminum killed steel, at least one of which was produced with a longer than average length. The muffler would be placed between the exhaust pipe and the tail pipe and if the distance between the two were significantly less than the nipple-to-nipple length of the muffler, the extended length nipple could be trimmed so as to allow the muffler to fit between the exhaust and tail pipes. Further, if it were found that the diameters of the exhaust and tail pipes were too large for the nipples provided on the mufflers, the nipples could be open up to a wider diameter by swaging or otherwise expanding. Examples of such mufflers are disclosed in U.S. Pat. No. 4,164,267, dated Aug. 14, 1979 to Meineke et al., which has since been dedicated to the public, U.S. Pat. No. 4,279,326 dated July 21, 1981, also to Meineke et al., and in the American Muffler Corporation Exhaust Parts Catalog cited in U.S. Pat. No. 4,279,326.
Although the "universal" mufflers can be used on a wide range of automobiles, each type of universal muffler described above has its drawbacks. For example, the universal muffler having the adjustable length muffler body is rather complex, expensive to manufacture, and limited in internal configuration. The universal mufflers having the aluminum killed steel nipples require a considerable amount of time to install and the replacement is not as aesthetically acceptable as that associated with the "made-to-fit" replacement. Further, the use of the universal mufflers having the aluminum killed steel nipples requires specialized apparatus, such as a swaging tool for increasing the nipple diameters if necessary.